A variety of different techniques are available for determining the state of intoxication or lack thereof of individuals. Some techniques are medically based, and involve drawing a sample of blood which is then analyzed. Other techniques require a person to exhale a deep lung breath sample directly into a breath sampling device or breathalyzer. The breathalyzer detects and measures the presence and concentration of alcohol (ethanol) in the exhaled breath sample, and correlates the measured alcohol content to a blood alcohol concentration in the individual. By requiring that the individual exhale directly into the breathalyzer, the breath sample is more accurately related to the alcohol content of the gas within the lungs, and consequently the blood alcohol content. Measuring the alcohol content of the directly exhaled breath sample also reduces the problems of having to account for and correct various variables which introduce errors in measurement.
Although not intrusive into the physical body of the individual subjected to the test, the person must directly interact with the breathalyzer when exhaling the lung gas sample into the machine. Such interaction is usually considered offensive or embarrassing, and people will not normally voluntarily submit to such tests unless such tests are enforced by law enforcement authorities. Enforced breathalyzer tests are usually carried out in police stations or other locations where the breathalyzer is permanently located, because most breathalyzers are sensitive to a wide variety of destabilizing effects. It is considered better practice to avoid moving the breathalyzers than to subject them to situations which could alter their calibration, particularly since the breath alcohol content data obtained from such machines might be used as evidence in legal proceedings.
Other types of breathalyzer devices are known which function in response to breath samples that have not been exhaled directly into the device. Such devices are generally not considered reliable, because of the significant differences between the measured alcohol content and the actual blood alcohol content of the individual giving the breath sample. The inaccuracy in such machines generally results from a failure or inability to account for important environmental and other variables which can significantly influence the breath alcohol content data obtained.
In addition to the most common uses of breathalyzers by law enforcement authorities, there is an increasing demand for use of breathalyzers in private enterprise. For example, owners of liquor serving establishments may wish to check the condition of their patrons before serving further liquor to them, to avoid potential legal liability for the acts committed by the patrons while intoxicated. Employers may wish to test the condition of their employees to detect deficiencies in performance. Medical authorities in alcohol treatment centers may wish to monitor the condition of their patients. Even law enforcement authorities would find a portable, non-invasive breathalyzer which does not require the person to directly exhale into it and which still delivers accurate data, a substantial benefit and assistance in their duties of determining whether a suspect is intoxicated. These examples of potential uses all require, or consider desirable, a small portable breathalyzer which does not require the individual to breath directly into it, but yet still obtains a very high degree of accuracy in the measured breath alcohol content.